February 28, 2026
How Airlines Get Their Codes: IATA Airline Designators Explained
Every airline has a two-letter IATA designator that appears on flight numbers, tickets, and booking systems. Here is how they are assigned and what happens when airlines merge or rebrand.
When you book a flight on United Airlines as UA 123 or British Airways as BA 489, those two letters before the flight number are the airline's IATA airline designator. These codes are distinct from airport codes and follow their own assignment system.
How IATA airline codes work
IATA assigns two-letter designators to airlines that carry passengers on scheduled international or domestic routes. The codes must be unique within the IATA system — unlike airport codes, which are unique globally, airline codes are scoped to active carriers. When an airline ceases operations, its code eventually becomes available for reassignment.
Famous IATA airline codes
- AA — American Airlines
- BA — British Airways
- EK — Emirates
- LH — Lufthansa
- QF — Qantas
- SQ — Singapore Airlines
- UA — United Airlines
Mergers and code changes
When airlines merge, IATA codes present a coordination challenge. When US Airways merged with American Airlines, the combined carrier kept AA but retired US. When Continental merged with United, UA was retained. In each case, the surviving code is chosen to minimize disruption to booking systems and frequent flyer programs.
ICAO airline codes
Separately, ICAO assigns three-letter telephony designators (also called ICAO airline codes) used in flight plans and air traffic control. These are different from IATA codes — American Airlines is AA in IATA but AAL in ICAO, British Airways is BA in IATA but BAW in ICAO. Browse our airlines directory to see both codes for every carrier.